"""生成链路的显式灰度开关。"""
import os
import hashlib


DEFAULTS = {
    "DOCUMENT_IR_V1": True,
    "PLAN_SNAPSHOT_V1": True,
    "SCENARIO_ENGINE_V2": False,
    "OUTPUT_RECONCILIATION_V1": True,
    "RETENTION_CLEANUP_V1": False,
}


def enabled(name: str) -> bool:
    if name not in DEFAULTS:
        raise KeyError(f"unknown feature flag: {name}")
    value = os.getenv(f"INSURANCE_{name}")
    if value is None:
        return DEFAULTS[name]
    return value.strip().lower() in {"1", "true", "yes", "on"}


def public_flags() -> dict[str, bool]:
    return {name: enabled(name) for name in DEFAULTS}


def enabled_for(name: str, *, identity: str = "", profile: str = "") -> bool:
    """支持按 profile 白名单和稳定百分比分桶的灰度判断。"""
    if not enabled(name):
        return False
    profiles = {
        item.strip() for item in os.getenv(f"INSURANCE_{name}_PROFILES", "").split(",")
        if item.strip()
    }
    if profiles and profile not in profiles:
        return False
    percentage = _percentage(name)
    if percentage >= 100:
        return True
    if percentage <= 0 or not identity:
        return False
    bucket = int(hashlib.sha256(f"{name}:{identity}".encode("utf-8")).hexdigest()[:8], 16) % 100
    return bucket < percentage


def rollout_config() -> dict:
    return {
        name: {
            "enabled": enabled(name),
            "percentage": _percentage(name),
            "profiles": [item for item in os.getenv(f"INSURANCE_{name}_PROFILES", "").split(",") if item],
        }
        for name in DEFAULTS
    }


def _percentage(name: str) -> int:
    try:
        return max(0, min(100, int(os.getenv(f"INSURANCE_{name}_PERCENT", "100"))))
    except ValueError:
        return 0